DESCRIPTION: (Applicant's Abstract) Hepatitis C (HCV) is currently the most prevalent life threatening disease among injection drug users, and complications from chronic HCV infection are likely to increase dramatically in this population in the next several years. Drug treatment programs are uniquely situated to provide critical HCV services to both IDUs and non-injecting drug users. Currently, however, there is virtually no systematic information about the drug treatment field's response to the HCV epidemic. The main purposes of the research are, therefore, to: (1) measure the extent to which three types of HCV services (education and counseling, antibody testing, and medical management and monitoring) are provided by a nationwide sample (N=800) of drug treatment programs, and compare the level of HCV related services across drug treatment modalities; (2) model the level of HCV services that these drug treatment programs provide on the basis of client characteristics, organizational structure and resources, relationships with public health organizations in the programs' environment, internal support for medical services, and the provision of other medical services (especially services for HIV and hepatitis A and B); (3) conduct case studies (N=24) of drug treatment programs in order to understand the innovation process (i.e., the adoption and development of HCV services) and the current implementation process (HCV service delivery practices and procedures); and (4) understand clients' perceptions of HCV services and the service delivery process in the case study sites, and whether their perceptions are congruent with those of staff. The research will analyze quantitative survey data to assess the structure of HCV services, and qualitative case study data to assess the innovation and implementation processes. The dissemination of research findings to the drug treatment field is expected to elevate consciousness about the need to properly respond to the HCV epidemic, assist advocates for HCV services in fostering the development of services, and assist programs that want to enhance services by informing them about "best practices."